External Power Connector

Douglas W Jones wrote:

I've got a Tektronix 321 scope (serial number 001917) that I need to run from an external
DC supply. The problem is, I have only the line cord, and not the
DC cord. The power input plugs on the scope are obviously
custom, long predating the standard IEC plug everyone uses today.
So I improvised. The pin spacing for the 3-pin DC input plug is
very close to the spacing of Molex 6, 9 and 12-pin plugs, and the
pin diameter is not too much larger than Molex uses. So, I
picked up a 6-pin Molex housing and 3 female molex pins, and
then cut the housing down to 4 pins (using my pocket knife).
I used an old IEC cord for the DC input wires, with the plugs cut
off both ends. I attached the wires on one end to the molex pins
and pushed them into the housing, then jammed to housing down
onto the Tektronix connector (this flared the female Molex pins
to fit the Tektronix pins. The other end of the DC power cord got
banana plugs to fit the output posts of my DC power supply.
The net result works fine, plugs and unplugs nicely, and unlike
other power supply solutions I've seen, involves no changes to
the scope.

321 External Power Connector

Douglas W Jones' 321 External Power Cable

Added note: My bench supply has an analog Ammeter on it.
The starting surge of the 321 is about 1.5 amps, perhaps 2,
tapering down to 0.7 amps in under a second. It seems to draw
a steady 0.7A regardless of what you're doing with it. The
current drain doesn't change when you vary the supply from 12 to
18V — this is because the 321 uses a linear regulator.